The use of composite materials for the manufacture of structural components has expanded considerably over the past years. In particular, composite materials made of carbon fibers and epoxy resins have been successfully used for the manufacture of various types of vehicles (e.g. cars, boats and airplanes). In part, this has happened because these materials are relatively light-weight, and they exhibit high strength in both tension and compression. They are also quite damage tolerant and resistant to puncture. Further, they inhibit water migration. Despite these many virtues, when composite materials are made into panels, and they do not have proper support, they are susceptible to buckling and can be floppy.
From a structural perspective, it is well known that the ability of a beam to resist being bent can be enhanced by adding material to the beam in its plane of bending. An I-beam is a good example of this and, in many respects, a panel is essentially no different. For instance, a panel exhibits a very high resistance to bending when forces are directed against the panel only in the plane where its material is located. On the other hand, a panel tends to buckle and flop when it is subjected to forces that are directed transverse to the plane of the panel. In this latter case, there is no material in the panel that can effectively react to the forces. A solution here is to reinforce the panel by positioning reactive material at a distance from the plane of the panel.
Early attempts to reinforce and stiffen composite material panels have typically involved using separate layers of the material. More specifically, these layers are held and distanced from each other by a honeycomb construction. While generally effective, these reinforced composite material panels are susceptible to separation between the layers of composite material and the honeycomb construction. As is well known, such separations weaken the panel. It also happens that such panels can become porous and, thus, be susceptible to moisture migration through the structure. In the case of vehicles, this moisture migration can lead to the corrosion of other structural components that can adversely affect the operation of the vehicle.
In light of the above, it is an object of the present invention to provide a reinforced panel that is made of a composite material, as well as its method of manufacture, wherein the panel is rigid and stiff. Another object of the present invention is to provide a reinforced panel and its method of manufacture that resists material separations which otherwise diminish the structural strength of the panel. Still another object of the present invention is to provide a reinforced panel and its method of manufacture, wherein the panel is non-porous and effectively prevents water migration in the panel. Yet another object of the present invention is to provide a method for manufacturing a reinforce panel that is made entirely of a composite material, wherein the method is easy to implement and is cost effective.